【作者】 邱洪波；

【导师】 李伟力；

【作者基本信息】 哈尔滨理工大学 ， 电机与电器， 2014， 博士

【摘要】 高速永磁发电机具有体积小、噪音低、动态响应快、功率密度大、传动系统效率高等优点,已成为微型燃气轮机分布式供能系统的关键发电设备,满足微型燃气轮机发电系统朝着小型化和集成化方向发展的要求。作为便携电源的发电设备,高速永磁发电机已广泛应用在军事、医疗、矿山救助等领域；作为机械形式的不间断电源(飞轮储能)与化学储能相比具有环境友好、寿命长等优势,可以广泛应用在航天、工业、通讯机网络服务等领域。高速永磁电机转速高、功率密度大,同样造成了电机单位损耗相对较大,而且气隙内的高频磁场将直接在护套和永磁体内产生涡流,形成涡流损耗,增加了转子的温升；由于永磁体在高温环境下易出现热退磁问题,而且相同功率电机体积小,转子散热相对困难,转子内的涡流损耗将直接威胁高速永磁发电机的安全运行,因此对于高速永磁发电机转子涡流损耗准确计算及降低转子涡流损耗方面的研究具有重要意义。针对定子背绕式绕组、转子合金护套结构的100kW级高速永磁电机的转子涡流损耗开展了深入的研究,基于三维时步有限元计算方法,对高速永磁电机转子涡流损耗进行了计算,深入研究了护套和永磁体内涡流电密的分布规律；建立了转子涡流损耗解析计算模型,对高速永磁电机护套和永磁体内的涡流损耗进行了解析公式推导,并与三维有限元涡流损耗计算结果进行了对比,突出体现了解析计算方法的快速性、通用性以及变量间影响关系明确的优势；分别利用三维有限元计算与解析计算方法,分析了护套轴向分段和永磁体圆周方向分段对转子涡流损耗的影响关系,揭示了转子分段在减小转子涡流损耗方面的作用机理,并提出了转子永磁体分段数量确定的依据与准则,满足高速永磁电机降低转子涡流损耗的设计要求。在降低转子涡流损耗方面,针对于转子护套自身材料电磁特性对电机电磁场的影响进行了深入的研究；在给出护套材料电磁特性的基础上,研究了护套材料的改变引起的电机电磁场、转子表面涡流电密及损耗的变化情况；基于电磁场透入深度理论,提出了合金护套转子表面镀铜的方法,解决了高速永磁电机护套高涡流密度的问题,并与现有的永磁电机铜屏蔽方法进行了对比,验证了转子表面镀铜在降低转子涡流损耗方面的优势。建立了永磁电机等效磁路模型,提出了永磁体漏磁系数迭代收敛的方法来确定永磁体励磁边界条件,采用向量磁位对不同磁导率护套的高速永磁发电机空载感应电动势进行了解析公式推导；改变永磁电机护套采用非铁磁材料的思维,创新提出弱磁性护套高速永磁电机的结构形式,充分发挥了弱磁性护套减小主磁路磁阻,提升永磁体工作点,提高永磁体材料利用率的优势,探索研究了护套磁导率对发电机空载感应电动势的影响,得出了护套磁导率调磁特性曲线；对定子绕组磁动势进行面电流等效,基于磁场叠加原理,对发电机负载运行时气隙及转子护套内的磁场进行了解析计算,根据坡印亭能量流传定理,求出了护套磁导率不同时,高速永磁发电机定转子间能量流传的大小；同时结合时步有限元计算方法,对比研究了护套材料磁导率的变化对电机磁场分布的影响,揭示了永磁体工作点随护套磁导率的变化规律,全面系统地分析了高速永磁电机主磁通、漏磁通、永磁体工作点间的相互影响关系,确定了护套磁导率的优化策略,最大限度发挥弱磁性护套的优势；此外针对转子护套电导率对转子表面涡流损耗的影响进行了研究,综合谐波透入深度理论、涡流损耗影响因素,深入阐述了转子表面涡流损耗随护套电导率的双因素非线性变化机理,获取了转子涡流损耗相对较大时,转子护套电导率的取值范围。建立电机电磁场与整流负载一体化仿真模型,构建整流负载高速永磁发电机试验系统,对比研究三相桥式整流负载对电机电磁场的影响,结合傅里叶变换理论,对发电机输出电压和电流的谐波进行了分析,给出了发电机整流负载运行时电流的各次谐波占有率和电流谐波总畸变率；然后分别计算了发电机电阻性负载和整流负载运行时,电机转子部分涡流损耗的变化,并对损耗变化的机理进行了研究；此外对比分析了这两种负载状态下发电机输出电压的变化情况,通过对非线性负载功率因数的计算,揭示了发电机输出电压变化的机理。建立了高速永磁发电机的三维流体与温度耦合计算模型,在电磁场损耗计算的基础上,对发电机转子护套材料、转子复合结构、护套电磁特性、负载性质对电机内温度场的影响进行了研究,对比分析了不同转子结构电机内定转子温升变化情况,并给出了不同转子结构下转子永磁体温度的分布,对防止高速永磁电机永磁体热退磁具有重要的意义。更多还原

【Abstract】 Due to the advantages of small size, low noise, fast dynamic response, high power density and high transmission efficiency, the high speed permanent magnet generator (HSPMG) has become a critical equipment in microturbine distributed energy supply system and could meet the requirements of the power system developing towards to the miniaturization and integration. As the’ generation equipment in portable power, HSPMG has been used widely in military, medical and mine rescue. As a mechanical form of uninterruptible power supply(flywheel energy storage), compared with the chemical energy storage, it is friendly with the working environment and has the longer life, so it can be widely used in aerospace, industrial and computer netword services. In the HSPMG, the higher power density could cause the larger losses in unit volume. The high frequency harmonic magnetic field in the air gap could induce the eddy current in the rotor sleeve and permanent magnets, which will cause the eddy current losses and increase the temperature of the rotor directly. Since the permanent magnets working in high temperature environment could be demagnetized, the eddy current losses could directly affect the normal operation of the generator. So it is of significance to have some researches on rotor eddy current losses.According to the special structure of a100kW level HSPMG, including the stator back wound windings and rotor alloy sleeve, the eddy current losses in the rotor sleeve and permanent magnets are studied. Based on the three-dimensional time-stepping finite element method, the rotor eddy current losses are calculated accurately, and the eddy current distribution in the rotor sleeve and permanent magnets could be obtained. Establishing the analytical calculation model of the surface mounted permanent magnet machine, the rotor eddy current loss expression could be derived, and the calculation results are compared with the finite element calculation results. It proves that the analytical method has the advantages of rapidity and universality. Combined with the3D finite element analysis and the analytical calculation method, the influences of the rotor sleeve segmenting in axial direction and the permanent magnets segmenting in circumferential diection on rotor eddy current losses are studied. Based on the above analyses, the principles of the permanent magnet segmenting are obtained.In order to reduce the eddy current losses, the influence of the sleeve materials on generator is studied. The variations of the electromagnetic field, eddy current density and eddy current losses are analyzed, when the electromagnetic property of the sleeve material is given. Based on the theory of harmonic field penetration depth, the copper plating which could reduce effectively the rotor eddy current losses is presented, which is also analyzed compared with the copper shield. The resulets show that the copper plating is a better way to reduce the rotor eddy current losses.The equivalent magnetic circuit model of HSPMG is established. In order to determine the boundary condition of permanent magnets, the iterative method of leakage coefficient is presented. The ferromagnetic material sleeve is adopted in the HSPMG, which could reduce the reluctance of the main magnetic circuit, improve the operating point and material utilization of permanent magnets. Using the vector magnetic potential, the induced noload electromotive forces of the HSPMG with different permeability sleeves are calculated analytically. And therewith the influence of the sleeve permeability on the induced electromotive force is analyed. The adjusting magnetic field character curve of sleeve permeability could also be obtained. Based on the priciple of the magnetic field superposition and the equivalent current sheet of fundamental MMF, the magnetic fields in the air gap and the rotor sleeve are calculated analytically when the generator operating at rated load. According to the Poynting Vector, the generator electromagnetic power transmitting from the rotor to the stator is calculated when the generator adopting different permeability sleeves. And therewith combined with the finite element method, the influence of the sleeve permeability on the generator magnetic field is studied comparatively. The relationship of the operating point of permanent magnets, the main flux and leakage flux is further analyzed. The optimal strategy is presented, which could take advantages of ferromagnetic material sleeve. In addition, the influence of the sleeve conductivity on rotor eddy current losses is also analyzed. According to the theory of the harmonic field penetration depth and the influence factors of the rotor eddy current losses, the variation principles of the eddy current losses with different conductivity sleeves are discovered. The range of the sleeve conductivity of the generator which will generate larger eddy current losses is given.The influence of the three-phase bridge rectifier load on the HSPMG is studied comparatively based on the field-circuit coupling electromagnetic model and the test plat. According to the Fourier transform theory, the voltage harmonics and current harmonics are studied. The content rate of the current harmonics and the current Total Harmonic Distortion(THD) are obtained. In addition, the rotor eddy current losses are ananlyzed comparatively, when the generator connected with the rectifier load and the resistance load respectively. With the same output power, the variations of the output voltage and the power factor of the generator with different loads are further analyzed.The3D coupling field between the fluid and temperature is established based on the calculation of the generator losses. And the influences of the rotor sleeve materials, the rotor structure, the electromagnetic properties of sleeve and the form of the load on the generator temperature field are studied. The temperature variations in different parts of the generator are given when the HSPMG adopts different rotors and loads respectively. The influences on the temperature of permanent magnets are further analyzed, and it is very important for the research on the permanent magnet demagnetizing.更多还原